Akademik Arşiv / Academic Archive
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Publication 2014-2020 Yılları Arasında Muhasebe Ve Finansman Dergisi’nde Yayınlanan Makalelerin Bibliyometrik Profilinin İncelenmesi(2021) Funda KARAASLANOĞLU Elif Tuğba ŞAHİN; Şahin, Elif Tuğba; Karaaslanoğlu, Funda; Türk Hava Kurumu Üniversitesi, İşletme Fakültesi, Ankara, Türkiye Türk Hava Kurumu Üniversitesi, İşletme Fakültesi, Ankara, TürkiyeBu çalışmada, 2014-2020 yılları arasında muhasebe ve finans alanının öncül dergilerinden Muhasebe ve Finansman Dergisi’nde yer alan makalelerin, çeşitli parametreler çerçevesinde bibliyometrik özelliklerinin belirlenmesi amaçlanmaktadır. Çalışmada, içerik analizi yöntemi ile 370 makale incelenerek mevcut durum ortaya konulmuştur. Araştırma bulgularına göre, en çok makalenin 2020 yılı, en az makalenin 2014 yılında yayınlandığı; makalelerde nitel araştırma yöntemlerinin nicel araştırma yöntemlerine oranla daha fazla kullanıldığı tespit edilmiştir. İçerik Analizi ve Örnek Olay Analizi, makalelerde en çok kullanılan analiz teknikleridir. Yayınlanan makalelerin sayfa sayılarının en az 12, en çok 32 olduğu, makalelerde yerli kaynaklardan daha fazla yabancı kaynaklardan yararlanıldığı tespit edilmiştir. Makalelerin en çok Uludağ Üniversitesi, Dokuz Eylül Üniversitesi ve Burdur Mehmet Akif Ersoy Üniversitesi’nde çalışan yazarlar tarafından hazırlandığı, yayınlanan 370 makale içinde en az 2014 yılında 136 ve en fazla 2020 yılında 250 anahtar kelime olmak üzere toplamda 1.393 anahtar kelime kullanıldığı belirlenmiştir. En fazla çalışmanın Doktor Öğretim Üyeleri tarafından yazıldığı belirlenmiştir.Publication 2D hybrid meshes for direct simulation Monte Carlo solvers(IOP Publishing, 2013-02-08) N Sengil; U SengilPublication 3-State Protein Secondary Structure Prediction based on SCOPe Classes(FapUNIFESP (SciELO), 2021) Sema Atasever; Nuh Azgınoglu; Hasan Erbay; Zafer AydınPublication 3D numerical modeling of boiling in a microchannel by arbitrary Lagrangian–Eulerian (ALE) method(Elsevier BV, 2016-01) Rahim Jafari; Tuba Okutucu-Özyurt; Jafari, RahimPublication 4G/LTE Technology For Smart Grid Communication Infrastructure(IEEE, 2015) Gozde, Haluk; Taplamacioglu, M. Cengiz; Ari, Murat; Shalaf, Hamza; Gazi University; Cankiri Karatekin University; Turk Hava Kurumu University; Turkish Aeronautical AssociationThe smart grid concept has emerged as a new trend to operate and manage the electric power systems more effective and efficient in recent years as different from centralized and distributed power systems. In this concept, the electric energy consumption is optimized by using an advanced automation system which needs more information about the power system elements from generation units to end-users and controls them in light of this information. Undoubtedly, receiving and transmitting of this information requires two-way, high speed, reliable and secure communication infrastructure. In this study, Long Term Evolution (LTE) technology and its usage in smart grid infrastructure are investigated. Additionally, the challenges for using 4G/LTE in smart grid applications are also discussed.Publication A 120 MHz fast automatic tuning CMOS active-RC lowpass filter(ELSEVIER SCI LTD, 2023) Yesil, Ercem; Zencir, Ertan; Zencir, Ertan; Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); Turk Hava Kurumu University; Turkish Aeronautical AssociationIn this paper, a fast automatic cutoff frequency calibrating, CMOS lowpass filter with linear-in-dB tunable gain and constant in-band group delay is presented. The automatic frequency tuning (AFT) circuit can successfully tune the cutoff frequency to 120 MHz with less than 4.7% error. In-band group delay variation is handled using a capacitor process variation detection circuit (CPVD), and the overall tuning time is less than 700 ns. The design is done using STM PD-SOI 130 nm CMOS process, and the supply voltage is 1.2 V with a total power consumption of 21.7 mW. The overall filter provides a programmable linear-in-dB gain of 0.5 dB to 17.6 dB range with a cutoff tuning range of 80 to 180 MHz. The in-band group delay variation is below 500 ps with an adjacent channel ratio (ACR) of 85 dB. The spurious free dynamic range (SFDR) is over 66.6 dBc. The active area of the filter with tuning is 0.171 mm2.Publication A combined experimental and theoretical study on 8-hydroxy-2-quinolinecarboxylic acid(Pleiades Publishing Ltd, 2014-02) Serdar Badoğlu; S̨enay Yurdakul; Badoğlu, SerdarPublication A compact octagonal-ring monopole antenna for super wideband applications(WILEY, 2020) Okan, Tayfun; Turkish Aeronautical Association; Turk Hava Kurumu UniversityA compact monopole super wideband antenna has been designed and fabricated in this study. The proposed antenna consists of an octagonal-ring shaped patch with a stub positioned on the top right corner of it to enhance the impedance bandwidth. Further improvement is ensured by optimally shifting both the patch and feed line away from the center line, and introducing a notch on the ground plane. The fabricated antenna covers the frequency band from 2.59 to 31.14 GHz with a reflection coefficient of |S-11| <= - 10 dB. It has a bandwidth of 28.55 GHz, fractal bandwidth percentage of 169% and bandwidth ratio of 12.02:1. Omnidirectional radiation characteristics are observed over the operating bandwidth in the far-field measurements. Furthermore, the far-field radar cross section measurement of the antenna is also simulated on PC and relatively low values are obtained through the operating bandwidth. Presented antenna has a relatively small size (40 x 40 x 1.01 mm(3)) and exhibits good gain and efficiency characteristics in comparison to studies with similar bandwidth.Publication A Comparative Analysis of Global Competition: North Atlantic Treaty Organization and Shanghai Cooperation Organization(Erciyes Universitesi, 2018-12-28) Ayça EMİNOĞLU; Sertif DEMİRBu makalenin amacı, Türkiye’de gündemde olan Avrasyacılık tartışmaları bağlamında iki örgütün karşılaştırmalı analizini yapmak ve böylece NATO ve ŞİÖ’nün benzerliklerini ve farklılıklarını ortaya koymaktır. Bu amaçla örgütlerin, kuruluş amaçları ve sınıflandırılmaları, kuruluş süreçleri, ittifak yükümlükleri, tehdit algılamaları, üyelerin nitelikleri, karar alma sistemleri, sorumluluk sahaları ve etkinlikleri karşılaştırma yöntemi ile analiz edilmiştir. Yapılan analiz sonucunda, bazı benzerliklere rağmen, NATO ile ŞİÖ arasında nitelik, nitelik, amaç ve kapsam açısından önemli farklar olduğu tespit edilmiştir. Türkiye NATO yükümlülüklerine zarar vermeden ŞİÖ ile yakın işbirliği yapması olası görünmektedir.Publication A comparative study of spreading of novel corona virus disease by ussing fractional order modified SEIR model(Elsevier BV, 2021-02) Hussam Alrabaiah; Muhammad Arfan; Kamal Shah; Ibrahim Mahariq; Aman UllahPublication A comparative study on utilizing hybrid-type nanofluid in plate heat exchangers with different number of plates(SPRINGER HEIDELBERG, 2020) Gurbuz, Emine Yagiz; Sozen, Adnan; Variyenli, Halil Ibrahim; Khanlari, Ataollah; Tuncer, Azim Dogus; Mugla Sitki Kocman University; Gazi University; Gazi University; Turk Hava Kurumu University; Turkish Aeronautical Association; Mehmet Akif Ersoy UniversityDifferent methods have been utilized to enhance the thermal efficiency of the heat exchangers (HEs). A widely used method to upgrade the thermal efficiency of HEs is upgrading the thermal properties of working fluid by utilizing nanoparticles. In this study, Al(2)O(3)and CuO have been utilized to prepare Al2O3-CuO/water hybrid nanofluid. Accordingly, Al(2)O(3)and CuO nanoparticles have been mixed into the water with 1% (50:50) weight concentration. The main objective of this work is testing the prepared hybrid nanofluid in plate-type HEs (PHEs) with 8, 12 and 16 plates to determine the influence of number of plates on heat transfer improvement by hybrid nanofluid. Experimental findings of the present study demonstrated that utilizing Al2O3-CuO/water hybrid-type nanofluid in the PHE enhanced thermal efficiency notably in comparison with single-type nanofluids. Using this hybrid nanofluid increased the thermal performance in all PHEs with different number of plates. However, it is observed that increasing number of plates led to more increment in thermal performance by utilizing hybrid nanofluid. The highest increment in overall heat transfer coefficient was obtained as 12%, 19% and 20% in PHEs with eight, 12 and 16 plates, respectively. In addition, the highest enhancement in effectiveness was achieved as 10%, 11.7% and 16% in PHEs with eight, 12 and 16 plates, respectively.Publication A comparison of peptide amphiphile nanofiber macromolecular assembly strategies(SPRINGER, 2019) Dana, Aykutlu; Tekinay, Ayse B.; Tekin, E. Deniz; Tekin, Emine Deniz; Stanford University; Turk Hava Kurumu University; Turkish Aeronautical Association.Supramolecular peptide nanofibers that are composed of peptide amphiphile molecules have been widely used for many purposes from biomedical applications to energy conversion. The self-assembly mechanisms of these peptide nanofibers also provide convenient models for understanding the self-assembly mechanisms of various biological supramolecular systems; however, the current theoretical models that explain these mechanisms do not sufficiently explain the experimental results. In this study, we present a new way of modeling these nanofibers that better fits with the experimental data. Molecular dynamics simulations were applied to create model fibers using two different layer models and two different tilt angles. Strikingly, the fibers which were modeled to be tilting the peptide amphiphile molecules and/or tilting the plane were found to be more stable and consistent with the experiments.Publication A comparison of some control strategies for a non-integer order tuberculosis model(International Journal of Optimization and Control: Theories and Applications, 2019-04-15) Tuğba Akman YıldızThe aim of this paper is to investigate some optimal control strategies for a generalized tuberculosis model consisting of four compartments. We construct the model with the use of Caputo time fractional derivative. Contribution of distancing control, latent case finding control, case holding control and their combinations are discussed and the optimality system is obtained based on the Hamiltonian principle. Additionally, the non-negativity and boundedness of the solution are shown. We present some illustrative examples to determine the most effective strategy to minimize the number of infected people and maximize the number of susceptible individuals. Moreover, we discuss the contribution of the Caputo derivative and the order of the fractional derivative to efficiency of the control strategies.Publication A comparison of some control strategies for a non-integer order tuberculosis model(International Journal of Optimization and Control: Theories and Applications, 2019-04-15) Tuğba Akman YıldızThe aim of this paper is to investigate some optimal control strategies for a generalized tuberculosis model consisting of four compartments. We construct the model with the use of Caputo time fractional derivative. Contribution of distancing control, latent case finding control, case holding control and their combinations are discussed and the optimality system is obtained based on the Hamiltonian principle. Additionally, the non-negativity and boundedness of the solution are shown. We present some illustrative examples to determine the most effective strategy to minimize the number of infected people and maximize the number of susceptible individuals. Moreover, we discuss the contribution of the Caputo derivative and the order of the fractional derivative to efficiency of the control strategies.Publication A Complexity-Reduced ML Parametric Signal Reconstruction Method(Springer Science and Business Media LLC, 2011-02-20) Z. Deprem; K. Leblebicioglu; O. Arıkan; A. E. ÇetinPublication A Comprehensive Literature Survey on Logistics Strategy and Supply Chain Optimization in the Biomass Energy Sector(2023-01-01) Güner, Gürkan GüvenPublication A comprehensive survey on recent metaheuristics for feature selection(Elsevier BV, 2022-07) Tansel Dokeroglu; Ayça Deniz; Hakan Ezgi KizilozPublication A comprehensive survey on utilization of hybrid nanofluid in plate heat exchanger with various number of plates(EMERALD GROUP PUBLISHING LTD, 2022) Afshari, Faraz; Tuncer, Azim Dogus; Sozen, Adnan; Variyenli, Halil Ibrahim; Khanlari, Ataollah; Gurbuz, Emine Yagiz; Erzurum Technical University; Mehmet Akif Ersoy University; Gazi University; Gazi University; Turk Hava Kurumu University; Turkish Aeronautical Association; Mugla Sitki Kocman UniversityPurpose Using suspended nanoparticles in the base fluid is known as one of the most efficient ways for heat transfer augmentation and improving the thermal efficiency of various heat exchangers. Different types of nanofluids are available and used in different applications. The main purpose of this study is to investigate the effects of using hybrid nanofluid and number of plates on the performance of plate heat exchanger. In this study, TiO2/water single nanofluid and TiO2-Al2O3/water hybrid nanofluid with 1% particle weight ratio have been used to prepare hybrid nanofluid to use in plate type heat exchangers with three various number of plates including 8, 12 and 16. Design/methodology/approach The experiments have been conducted with the aim of examining the impact of plates number and used nanofluids on heat transfer enhancement. The performance tests have been done at 40 degrees C, 45 degrees C, 50 degrees C and 55 degrees C set outlet temperatures and in five various Reynolds numbers between 1,600 and 3,800. Also, numerical simulation has been applied to verify the heat and flow behavior inside the heat exchangers. Findings The results indicated that using both nanofluids raised the thermal performance of all tested exchangers which have a various number of plates. While the major outcomes of this study showed that TiO2-Al2O3/water hybrid nanofluid has priority when compared to TiO2/water single type nanofluid. Utilization of TiO2-Al2O3/water nanofluid led to obtaining an average improvement of 7.5%, 9.6% and 12.3% in heat transfer of heat exchangers with 8, 12 and 16 plates, respectively. Originality/value In the present work, experimental and numerical analyzes have been conducted to investigate the influence of using TiO2-Al2O3/water hybrid nanofluid in various plate heat exchangers. The attained findings showed successful utilization of TiO2-Al2O3/water nanofluid. Based on the obtained results increasing the number of plates in the heat exchanger caused to obtain more increment by using both types of nanofluids.Publication A Direct Numerical Simulation Study for Flame Structure and Propagation Characteristics of Multi-Jet Flames(TAYLOR & FRANCIS INC, 2023) Kiran, D.; Minamoto, Y.; Osawa, K.; Shimura, M.; Tanahashi, M.; Tokyo Institute of Technology; Turk Hava Kurumu University; Turkish Aeronautical Association; Universidad Politecnica de Madrid; Tokyo Institute of TechnologyLifted multi-jet flames of hydrogen and steam-diluted oxygen are studied using direct numerical simulations (DNS). The DNSs have been carried out for laminar and turbulent flame configurations. The simulation data are analyzed to investigate the flame and flame-base structures and the flame-base propagation in a configuration akin to a gas turbine with multiple fuel jets. The laminar flames have a tribrachial structure, although lean premixed and diffusi on flame branches collide downstream owing to preferential diffusion. The turbulent multi-jet flames have a single connected base region, whereas the laminar flames have separate bases, each of which is associated with the corresponding fuel jet. Although turbulent multi-jet flames have substantially different flame-base characteristics from laminar multi-jet flames (and conventional single-jet lifted flames), the propagation speed is similar for both conditions. The results suggest that the well-known flame-base stabilization theory can be straightforwardly applied to the multi-jet configuration, despite the turbulent flame structure's unconventional features.Publication A facile approach for the fabrication of antibacterial nanocomposites: A case study for AgNWs/Poly(1,4-Cyclohexanedimethylene Acetylene Dicarboxylate) composite networks by aza-Michael addition(PERGAMON-ELSEVIER SCIENCE LTD, 2022) Altinkok, Cagatay; Acik, Gokhan; Daglar, Ozgun; Durmaz, Hakan; Tunc, Ilknur; Agel, Esra; Istanbul Technical University; Trakya University; Turk Hava Kurumu University; Turkish Aeronautical Association; Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK)Nanotechnological improvements allow the production of new generation materials among which nanocomposite-based polymers are increasingly applied for wide variety of applications due to the demand increment of improving life quality of mankind. This article describes a simple, facile and fast route which could be adopted for the synthesis of metal nanocomposite materials with a variety of polymers. In this purpose, the cysteamine compound containing an amine (NH2) and a thiol (-SH) functional groups was incorporated onto silver nanowires (NH2-AgNWs). Next, poly(1,4-Cyclohexanedimethylene Acetylene Dicarboxylate) (PCA) possessing electron deficient internal alkyne moiety is synthesized starting from acetylene dicarboxylic acid (ADCA). Finally, one-pot aza-Michael addition is then realized between prepared NH2-AgNWs and synthesized PCA to achieve a series of cross-linked antibacterial nanocomposite networks (PCA:NH2-AgNWs = 1; 5; 10 wt%). The nanocomposites and intermediates are fully characterized by Fourier transform infrared and proton nuclear magnetic resonance (FT-IR, 1H NMR) spectroscopies, gel permeation chromatography (GPC) scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), thermogravimetric and differential scanning calorimetry analyses (TGA and DSC) and antibacterial test. The results reveal that the higher content of AgNWs in the network has occasioned the enhancement in thermostability and glass transition temperature. The antibacterial efficacy tests against Escherichia coli (E. coli, G) and Staphylococcus aureus (S.aureus, G +) further indicate that higher rate of inhibition is attained for nanocomposite network including 10 wt% AgNWs compared to others and pristine PCA. Consequently, a polyester based AgNWs/PCA nanocomposite with antibacterial activity has been considered as a versatile candidate for various promising nanocomposite applications.